Photosynthesis Flashcards
What type of organisms can perform photosynthesis?
Photoautotrophic organisms that contain chlorophyll, such as plants, algae and Cyanobacteria can perform photosynthesis
Where does the photosynthesis take place in eukaryotes?
Photosynthesis takes place in the mesophyll layer of the leaves. Chloroplast is present in the mesophyll layer, the chloroplast contains thylakoids in layers called granum. The chlorophyll is present in the thylakoid membrane. The fluid filled space outside granum is called stroma.
Where do light dependent and light independent reaction occurs?
Light dependent reaction occurs in the thylakoid of the chloroplasts.
Light independent reaction occurs in the fluid filled space called stroma of the chloroplasts.
What is light independent reaction called in other way?
Calvin cycle
What are the products of light dependent reaction?
Oxygen, ATP and NADPH
From sunlight+H20
What are photo systems?
Photosystems are complex proteins and pigments that absorb sunlight energy in light reactions.
Where are PS 1 and PS 2 present
In the thylakoid membranes of chloroplasts
What are PS 1 and PS 2 also called ?
PS 2= P 680 bcuz it absorbs light best at 680 nm
PS 1= P700 bcuz it absorbs light best at 700 nm.
What does photosynthesis start with?
Photosynthesis starts with when PS2 absorbs sunlight energy
How many kinds of pigments are in the plants and where do they present?
Chlorophyll pigments- A B C D
Molecules present in cyanobacterium
Carotenoid molecules present in the colors of the fruits, much larger pigment molecules
Chlorophyll a and b are present in higher plants chloroplasts.
What is the role of carotenoids in light dependent reaction?
To remove excess sunlight.
Briefly explain about the components of photosystem 2 on thylakoid membrane.
- Light harvesting complex= contain chlorophyll and carotenoid molecules and absorb sunlight energy and pass it from one another
- Reaction center- contain a pair of chlorophyll molecules with special property, when the molecules are excited, they can actually give off electrons to the primary electron acceptor on the reaction center.
From PS2 to PS 1, how are electrons transferred?
Electrons are transferred from high energy to low energy. Electrons are 1st transferred to plastoquinone Pq then to cytochrome complex then to plastocyanin Pc. Then the electrons reach PS1.
Why is H20 oxidized in light reaction ?
After PS 2 gives off electrons, it needs to be replaced with electrons and hence taking electrons from water molecules to produce H+ ions and O2.
How is H+ concentration increased in thylakoid?
By products from the oxiding of H20 molecules and by the hydrogen pumps pumping hydrogen from the stroma into thylakoid.
How are hydrogen ions used in photosynthesis light reactions?
NADP+ + H+=NADPH (reaction in stroma) results in the loss of protons ———>low H+
High H+ in thylakoid
Therefore creates hydrogen ions gradient. The energy obtained from the gradient is used in ATP synthesis ] by a channel called ATP synthase.
What is Calvin cycle also called?
Calvin cycle is also called dark reaction/ light independent reaction
When does Calvin cycle occur?
Both day and night like light reactions
How many stages are there in Calvin cycle?
3 stages
- Carbon fixation
- Reduction
- Regeneration
How many ATP and NADPH molecules are used in producing one glucose molecule in Calvin cycle.
18 ATP and 12 NADPH molecules
How many cycles is needed to repeat for one G3P molecule?
G3P has 3 carbon atoms hence 3 cycles of Calvin cycle is needed to repeat to fix enough carbon for one G3P molecule.
